Proteostasis Therapeutics Inc. closed its underwritten public offering of 9.2 million common shares priced at $5 apiece for net proceeds of about $42.9 million.

The shares sold included 1.2 million shares issued pursuant to the full exercise of the underwriters' option to buy additional shares.

Proteostasis plans to use the net proceeds to advance its double and triple combination therapies in dose-range-finding and proof-of-concept studies, to advance each of its double and triple combination therapies in phase 1 clinical trials in cystic fibrosis patients and for working capital and other general corporate purposes.

Leerink Partners LLC and RBC Capital Markets LLC acted as joint book-running managers and H.C. Wainwright & Co. LLC acted as lead manager for the offering.